The Polycomb group protein EZH2 directly controls DNA methylation

The mystery of tumor formation and progression has long plagued scientists and medical experts alike. However a new study into epigenetic gene silencing has uncovered a significant correlation between all stages of tumor formation and progression with Chromatin alterations.

The study demonstrated that epigenetically mediated transcriptional-silencing events that are associated with increases in DNA methylation — particularly at promoter regions of genes that regulate important cell function were generally present in situations of tumor formation and growth.

Genes encoding Ploycomb group(PcG) proteins were first identified in Drosophila as essential factors for the regulation of homeotic genes during development. PcG proteins are divided into two families in accordance with their physical associations in distinct multiprotein complexes termed Polycomb repressor complexes (PRCs). Enhancer of Zeste homolog (EZH2) is a particular protein within the Polycomb group. It is classified as a histone lysine methyltransferase (HKMT) and has been associated with tran-scriptional repression.

In this article, the authors certificated the connection of corresponding silencing pathways. They obtained the result that the PcG protein EZH2 interacts with DNA methyltransferases(DNMTs) and associates with DNA methyltransferase activity in vivo.

Furthermore, the proximate relationship identified between EZH2 and DNMTs might also be relevant to X-chromosome inactivation in female mammals. Consequently the research into the mechanistic link between the two essential epigenetic systems may be of substantial scientific significance.

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Yiwen Cui